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The LUX Dark Matter Search Status Update
Sixth TPC Symposium – Paris – December 17th, 2012 The LUX Dark Matter Search Status Update Exciting times in South Dakota
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Collaboration Meeting, UCSB March 2012
The LUX Collaboration Brown Richard Gaitskell PI, Professor Simon Fiorucci Research Associate Monica Pangilinan Postdoc Jeremy Chapman Graduate Student Carlos Hernandez Faham David Malling James Verbus SD School of Mines Xinhua Bai PI, Professor Texas A&M James White PI, Professor Robert Webb Professor Rachel Mannino Graduate Student Clement Sofka Case Western Thomas Shutt PI, Professor Dan Akerib Mike Dragowsky Research Associate Professor Tom Coffey Research Associate Carmen Carmona Postdoc Karen Gibson Adam Bradley Graduate Student Patrick Phelps Chang Lee Kati Pech Tim Ivancic UC Davis Mani Tripathi PI, Professor Robert Svoboda Professor Richard Lander Britt Hollbrook Senior Engineer John Thomson Senior Machinist Matthew Szydagis Postdoc Richard Ott Jeremy Mock Graduate Student James Morad Nick Walsh Michael Woods Sergey Uvarov Imperial College London Henrique Araujo PI, Senior Lecturer Tim Sumner Professor Alastair Currie Postdoc UC Santa Barbara Collaboration Meeting, UCSB March 2012 Lawrence Berkeley + UC Berkeley Harry Nelson PI, Professor Mike Witherell Professor Dean White Engineer Susanne Kyre Curt Nehrkorn Graduate Student Bob Jacobsen PI, Professor Victor Gehman Scientist David Taylor Engineer Mia ihm Graduate Student University of Rochester Yale Frank Wolfs PI, Professor Wojtek Skutski Senior Scientist Eryk Druszkiewicz Graduate Student Mongkol Moongweluwan Daniel McKinsey PI, Professor Peter Parker Professor James Nikkel Research Scientist Sidney Cahn Lecturer/Research Scientist Alexey Lyashenko Postdoc Ethan Bernard Markus Horn Blair Edwards Scott Hertel Kevin O’Sullivan Nicole Larsen Graduate Student Evan Pease Brian Tennyson University College London Lawrence Livermore Adam Bernstein PI, Leader of Adv. Detectors Group Dennis Carr Mechanical Technician Kareem Kazkaz Staff Physicist Peter Sorensen John Bower Engineer Chamkaur Ghag PI, Lecturer University of Edinburgh University of South Dakota Dongming Mei PI, Professor Chao Zhang Postdoc Dana Byram Graduate Student Chris Chiller Angela Chiller Alex Murphy PI, Reader James Dobson Postdoc Lea Reichhart Graduate student LIP Coimbra Isabel Lopes PI, Professor Jose Pinto da Cunha Assistant Professor Vladimir Solovov Senior Researcher Luiz de Viveiros Postdoc Alexander Lindote Francisco Neves Claudio Silva University of Maryland Carter Hall PI, Professor Attila Dobi Graduate Student Richard Knoche
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The LUX Experiment 370 kg xenon 122 PMTs 2” round
Thermosyphon Copper shield Water tank Top PMT array Anode grid PTFE reflector panels and field cage Detector stand Outer cryostat Inner cryostat Cathode grid 370 kg xenon 300 kg active region 100 kg fiducial 122 PMTs 2” round Low-background Ti cryostat Bottom PMT array
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Inverted steel pyramid
LUX Design – Water Tank Water Tank: d = 8 m, h = 6 m 300 tonnes, 3.5 m thickness on the sides Inverted steel pyramid (20 tonnes) under tank to increase shielding top/bottom Cherenkov muon veto Ultra-low background facility Gamma event rate reduction: ~10-9 High-E neutrons (>10 MeV): ~10-3 2.75 m 1.20 m 3.50 m Inverted steel pyramid Shield Thickness (m) Rock g m neutrons Rock neutrons Rendering by J. Thomson Slide design from L de Viveiros
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LUX Design – Deep Underground Operation
Cosmic Rays - Muons
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LUX Design – Self-shielding
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LUX – XENON100 Comparison Comparison of LUX and XENON100 data for the same exposure of 7600 kg.d, from the latest XENON100 result (July 2012). LUX data is simulated from known radioactive background components. The WIMP signal in red corresponds to a 100 GeV/c2 WIMP with a cross-section at the current best sensitivity limit of cm2. The ER background is one order of magnitude lower, allowing for a clearer detection signal or a stronger limit.
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The LUX Program 2007 – 2009 2010 – 2011 2012+
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Surface Lab – June 2009 to September 2010
Full-scale test of LUX deployment Liq/gas system PMT testing DAQ testing Water shield Xe purity June 2009 September 2010
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Surface Lab – August 2010 to February 2011
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Cryogenic Test: Success!
Surface Lab – May 2011 : Run 1 Cryogenic Test: Success!
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Surface Lab – July to October 2011
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Surface Lab – October 2011 to February 2012 : Run 2
Position resolution < 5mm Leak! 205 ms ~ 25 cm = ½ a LUX
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LUX Run 2 Summary List of major achievements already communicated to the World by February 2012 To which one can add: Working slow-control and alarm system, working muon veto, emergency storage system in place, working calibration system (external and internal), reviewed and tested operating and assembly procedures, no (work related) injuries over 17 months and > 38,500 total work hours… Negative points: Leak in condenser line limited purification capability (easily fixed) One PMT base stopped working (out of 122; now fixed) Used ~20-30 kg more Xenon to fill detector than anticipated (we have a lot to spare now) Drift field limited by flaws on Cathode grid wires (now replaced and tested) Did not find Dark Matter (neither did anyone else… probably) 120 V / cm (limited by electroluminescence on grid)
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Surface Lab – March to July 2012
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Sanford Lab – Davis Laboratory
Clean Room Breakout Control Room LN Storage Electronics Counting Facility Xe Balloon LUX Detector Cherenkov Water tank Excavation/construction started August 2009 finished June 2012 Gas System
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Davis Campus – Summer 2012 June 25 July 6 June 29 June 15 August 25
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Davis Campus – September 2012
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LUX Underground Physics Program
Oct 22 – Nov 7: Water Tank filled with water Oct 1 – Dec 6: Detector at vacuum Cherenkov data from PMT windows, PTFE Dec 7 – Jan 13: Detector warm with Xe gas Alpha events from Rn on internal surfaces Kr-83 for gas flow tomography Jan 14 – Feb 13: Cool-down + Condense Xe 400 kg of Xe with 5 ppt measured Kr is ready ~1 month to reach acceptable Xe purity ~2 months of non-blind WIMP search Including run parameters optimization ~1 month of additional calibrations First result by mid-2013 PTFE Cherenkov events Nov 7 October 22
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LUX WIMP Sensitivity Goal
CDMS II 2008 ZEPLIN III 2011 Edelweiss II 2011 XENON = LUX 4 days XENON = LUX 15 days LUX 300 days
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Because this was not long enough already…
Additional Slides
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LUX Design – Dual Phase Xenon TPC
Can measure single electrons and photons Charge yield reduced for nuclear recoils Excellent 3D imaging Reject multiple scatters Eliminate edge events to take advantage of Xe self shielding
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LZ uses the same water tank as LUX in the Davis Lab
LZ Program – Overview Born from the joining of LUX and ZEPLIN Construction Run (…?) New features compared to LUX Increased Xe mass : 7t total, 5t fiducial 482 3" PMTs at ~1 mBq radioactivity level Liquid Scintillator shield/veto Instrumented « dead » Xe space Improved Cherenkov veto coverage ...That’s it. Progress in sensitivity comes chiefly with: Increasing the Xe mass Scaling up existing LUX technology Xe self-shielding is driving the background rates down dramatically R&D effort ramping up since 2011, Project Management through LBNL LZ uses the same water tank as LUX in the Davis Lab
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LZ Program – WIMP Sensitivity Reach
XENON LUX 300 days x 7 x 175 LZ 1000 days
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